1. Field of the Invention
The present invention generally relates to a power control system for an Asynchronous Transfer Mode (ATM) system, and more particularly, to a time delayed control circuit with a power monitor to allow for hot insertion/hot swapping of a power module in an ATM system.
2. Description of the Related Art
In communication systems having distributed power architectures, such as, for example, Asynchronous Transfer Mode (ATM) systems, hot insertion/hot swapping of the power module is a requirement. That is, to perform maintenance, diagnostics, or testing, operators and technicians must be able to insert or remove the power module while the system is operating.
This hot insertion/hot swapping requirement, however, presents a problem for the RESET lines in an ATM system. The RESET lines connect redundancy masters (e.g., a power unit such as a System Power Unit (SPU)) with slave modules (e.g., System Interface Units (SIU)). Generally, either a specialized power supply design or the addition of special power isolation switches have been used in order to satisfy the hot insertion/hot swapping requirement.
Such methods have certain drawbacks. One is that a specialized power supply sequence requires additional relays, which increases the manufacturing and testing costs, complicates the design, and reduces product reliability. Moreover, additional switching controls are needed if special power isolation devices are used.
In light of the foregoing, there exists a need for a power control circuit that satisfies the hot insertion/hot swapping requirement of a distributed power system, and that is simpler, more reliable, and cost effective.